Film covers for sensor packages

ABSTRACT

In some examples, a sensor package includes a semiconductor die having a sensor; a mold compound covering a portion of the semiconductor die; and a cavity formed in a top surface of the mold compound, the sensor being in the cavity. The sensor package includes an adhesive abutting the top surface of the mold compound, and a semi-permeable film abutting the adhesive and covering the cavity. The semi-permeable film is approximately flush with at least four edges of the top surface of the mold compound.

BACKGROUND

Electrical circuits are formed on semiconductor dies and subsequentlypackaged inside mold compounds to protect the circuits from damage dueto elements external to the package, such as moisture, heat, and bluntforce. To facilitate communication with electronics external to thepackage, an electrical circuit within the package is electricallycoupled to conductive terminals. These conductive terminals arepositioned inside the package but are exposed to one or more externalsurfaces of the package. By coupling the conductive terminals toelectronics external to the package, a pathway is formed to exchangeelectrical signals between the electrical circuit within the package andthe electronics external to the package via the conductive terminals.

SUMMARY

In some examples, a sensor package includes a semiconductor die having asensor; a mold compound covering a portion of the semiconductor die; anda cavity formed in a top surface of the mold compound, the sensor beingin the cavity. The sensor package includes an adhesive abutting the topsurface of the mold compound, and a semi-permeable film abutting theadhesive and covering the cavity. The semi-permeable film isapproximately flush with at least four edges of the top surface of themold compound.

In some examples, a method comprises covering an array of semiconductordies with a mold compound, the mold compound having an array of cavitiesin a top surface of the mold compound. Each cavity in the array ofcavities is vertically aligned with a sensor of a correspondingsemiconductor die in the array of semiconductor dies. The methodcomprises coupling a semi-permeable film to the top surface of the moldcompound using an adhesive. The semi-permeable film covers the array ofcavities, and the semi-permeable film has an array of orifices. Themethod includes singulating the semiconductor dies in the array ofsemiconductor dies from each other to produce a sensor package. Thesensor package includes a portion of the adhesive, a portion of thesemi-permeable film, and an orifice of the array of orifices. Theorifice exposes the portion of the adhesive to an exterior of the sensorpackage.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of various examples, reference will now bemade to the accompanying drawings in which:

FIGS. 1A-7D are perspective, profile, and top-down views of a processflow for manufacturing a sensor package in accordance with variousexamples.

FIGS. 8A-19C are perspective, profile, and top-down views of anotherprocess flow for manufacturing a sensor package in accordance withvarious examples.

FIGS. 20A-25C are perspective, profile, and top-down views of anotherprocess flow for manufacturing a sensor package in accordance withvarious examples.

FIGS. 26A-32 are perspective, profile, top-down, and bottom-up views ofanother process flow for manufacturing a sensor package in accordancewith various examples.

FIGS. 33-36 are flow diagrams of methods for manufacturing sensorpackages in accordance with various examples.

DETAILED DESCRIPTION

Some types of packages are configured to measure various physicalproperties of an environment, such as temperature, humidity, light,sound, pressure, etc. In many instances, the package includes a sensorthat is exposed directly to the environment to be tested. Thus, forexample, a package that is configured to measure the temperature of aswimming pool may be positioned in an area of the pool where the sensorwill be directly exposed to the pool water. Such packages are referredto herein as sensor packages.

Sensor packages contain sensors, but they also contain other circuitry,such as an analog front-end (AFE) circuit, to process the properties ofthe environment sensed by the sensor. This circuitry cannot be exposedto the environment, as doing so could damage the circuitry and render itinoperable. Accordingly, sensor packages are fabricated so that thesensor is exposed to the environment, but the remaining circuitry of thepackage is covered by the mold compound of the package. A sensor packagemay include a cavity in its mold compound, and the sensor is positionedinside this cavity from a top view of the sensor package.

Existing designs for sensor packages are unsatisfactory for multiplereasons. One such reason relates to the manner in which sensors insensor packages are protected from exposure to dust, debris, pollution,and corrosive substances (e.g., flux, solder, cleaning solvents).Sensors are especially vulnerable to such exposure at the time thatsensor packages are coupled to printed circuit boards (PCBs), althoughexposure may happen at any time in the life cycle of a sensor. Suchexposure can negatively affect the life and performance of the sensor.To protect sensors from such exposure, existing sensor packages mayinclude a film that permits materials to be sensed (e.g., air for ahumidity sensor, pressure sensor, or sound sensor) to pass through thefilm and that prevents dust, debris, pollution, and corrosive substancesfrom touching the sensor. In some cases, these films cover the sensorpermanently, and in other instances, the films are manually removedafter the PCB-mounting process is complete. These films may be effectivein some instances, but they are applied manually or semi-manually withsome assistance from machines. As sensor packages and sensors continueto decrease in size over time, it has become increasingly difficult tomanually or semi-manually apply such films accurately. Not only are suchfilms often improperly applied, but even when they are properly applied,the manual or semi-manual technique by which they are applied istime-consuming, expensive, and limited in capacity.

This disclosure describes various examples of sensor packagemanufacturing techniques that overcome the challenges described above.In some examples, the techniques include covering a lead frame striphaving multiple semiconductor dies using a mold compound. The techniquesfurther include coupling one or more films to a top surface of the moldcompound. The techniques still further include singulating the moldcompound to produce a sensor package. The sensor package couples to aportion(s) of the one or more films. The one or more films protect thesensor and the top surface of the mold compound of the sensor package,e.g., from dust, debris, pollution, and/or corrosive substances. The oneor more films may be permanent or may be removable. For example, in someapplications, the film(s) may remain on the sensor package for the lifeof the sensor package, continuing to protect the sensor and the topsurface of the sensor package while the sensor package remains in use.In other applications, the film(s) may be removed after a dust, debris,pollution, and/or corrosive substance exposure risk has passed, forexample, after the sensor package has been coupled to a PCB.

By applying the film(s) to the mold compound pre-singulation and thensingulating the mold compound to produce individual sensor packages,several advantages are gained. First, the process is more accurate thanmanual application of films, as relatively large film(s) are applied torelatively large mold compounds, thus reducing or eliminating thesmall-scale precision work that introduces risk of inaccurate filmplacement. Second, large groups of sensor packages can be processedrelatively quickly, efficiently, and at reduced cost, with minimal humanintervention. Third, because the disclosed manufacturing techniques areperformed on a large scale, any adhesives that are used (e.g., to attachfilms to mold compounds) are prevented from excessive drying, thusimproving adhesive performance. Examples of such sensor packagemanufacturing techniques are now described with reference to thedrawings.

FIGS. 1A-7 are perspective, profile, and top-down views of a processflow for manufacturing a sensor package in accordance with variousexamples. FIG. 33 is a flow diagram of a method 3300 for manufacturingthe sensor packages of FIGS. 1A-7 in accordance with various examples.Accordingly, FIGS. 1A-7 and 33 are now described in tandem.

The method 3300 includes covering an array of semiconductor dies with amold compound (3302). The mold compound includes an array of sensorcavities in a top surface of the mold compound, with each sensor cavityin the array of sensor cavities vertically aligned with a sensor of acorresponding semiconductor die in the array of semiconductor dies(3302). FIG. 1A is a perspective view of a carrier 100 supporting a moldcompound 102 housing multiple semiconductor dies (not visible in FIG. 1Abut visible in FIG. 1C and described below), each semiconductor diehaving a sensor formed on an active surface of the semiconductor die.The sensors are configured to sense any of a variety of properties, suchas humidity, pressure, sound, light, temperature, etc. In some examples,a semiconductor die may have a single sensor, and in other examples, asemiconductor die may have multiple sensors. The remainder of thisdescription assumes that each semiconductor die includes a singlesensor, but the techniques described herein may be adapted forapplications in which multiple sensors are present on one or moresemiconductor dies. The mold compound 102 includes multiple sensorcavities 104, each sensor cavity 104 containing a different sensorcoupled to a different semiconductor die.

FIG. 1B is a top-down view of the structure of FIG. 1A. FIG. 1C is aprofile, cross-sectional view of the structure of FIG. 1A. FIG. 1C showsmultiple semiconductor dies 108, each semiconductor die 108 having adifferent sensor 106. Conductive terminals 110 are positioned on eachside of each semiconductor die 108. The conductive terminals 110 areomitted from the remaining drawings for ease and clarity of explanation,but the conductive terminals 110 are present on each sensor packageformed using the techniques described herein so as to facilitatesubsequent connections with a PCB. For example, the conductive terminals110 may be suitable for forming a quad flat no-lead (QFN) style sensorpackage.

The method 3300 comprises coupling a semi-permeable film to the topsurface of the mold compound using an adhesive (3304). Thesemi-permeable film covers the array of sensor cavities, and thesemi-permeable film includes an array of orifices (3304). FIG. 2 shows aperspective view of a semi-permeable film 200. In examples, thesemi-permeable film 200 comprises polytetrafluoroethylene (PTFE). Inother examples, the semi-permeable film 200 comprises expanded PTFE ormicro-porous PTFE formed from sintering. In examples, the permeabilityof the semi-permeable film 200 ranges from 100 nanometers to 10 microns,with greater permeability being advantageous because it allows fastergas exchange rates across the membrane while lesser permeability offersbetter liquid ingress protection under high pressure. A permeabilitygreater than this 100 nm to 10 micron range, however, can result inexcessive liquid ingress and a permeability less than this range mayresult in inadequately slow gas exchange. The semi-permeable film 200may have any suitable dimensions, including length, width, andthickness. FIG. 3 is a perspective view of the structure of FIG. 1A, butwith the addition of an adhesive 300 on a top surface of the moldcompound 102. In examples, the adhesive 300 includes acrylates oradhesion-modified polymers, although stronger or weaker adhesives anddifferent types of adhesives are contemplated. In examples, the adhesive300 has an adhesive strength ranging from 0.88 N/mm² to 1.81 N/mm². Insome examples, a stronger adhesive strength (e.g., at least 1.2 N/mm²)for the adhesive 300 is used, because in such examples thesemi-permeable film 200 may remain permanently coupled to the moldcompound 102 using the adhesive 300 for the lives of the sensors 106. Inexamples, such a strong adhesive strength may also be beneficial duringmanufacture, as insufficient adhesive strength for the adhesive 300 mayresult in slippage or movement of the semi-permeable film 200 during,e.g., singulation. This may be particularly problematic if thesemi-permeable film 200 is patterned, as in examples described below.

FIG. 4A is a perspective view of a patterned version of thesemi-permeable film 200. Specifically, the semi-permeable film 200 mayinclude optional orifices 402. In examples, when the semi-permeable film200 is coupled to the top surface of the mold compound 102 using theadhesive 300 and the mold compound 102 has been singulated intoindividual sensor packages, each orifice 402 is positioned closest topin 1 of the corresponding sensor package relative to the other pins ofthat sensor package. In this way, the orifice 402 of a sensor packageidentifies pin 1 of the sensor package. In examples, the orifices 402are triangular. In examples, the orifices 402 are circular. In someexamples, after the semi-permeable film 200 is coupled to the topsurface of the mold compound 102 and the mold compound 102 issingulated, each orifice 402 occupies a corner of the top surface of thecorresponding sensor package (e.g., after singulation, the orifice 402on a sensor package is not circumscribed by the semi-permeable film200), and in other examples, the orifices 402 do not occupy a corner ofthe top surface of the corresponding sensor package (e.g., aftersingulation, the orifice 402 on a sensor package is circumscribed by thesemi-permeable film 200). In examples, orifices 402 that do not occupy acorner of the top surface of a corresponding sensor package may resultin semi-permeable films 200 that are more easily and quickly alignedwith the top surface of the mold compound 102 than would be the casewith orifices 402 that do occupy a corner of the top surface of acorresponding sensor package, due to the precise alignment associatedwith corner orifices 402. In addition, in some examples, a strongeradhesive (e.g., greater than or equal to the minimum adhesive strengthprovided above) may be used when orifices 402 should have precisionalignment, for example, when orifices 402 occupy corners of the topsurfaces of corresponding sensor packages. The orifices 402 may beformed using any suitable technique, such as laser, die-cut, etc. FIG.4B is a top-down view of the structure of FIG. 4A.

FIG. 5A is a perspective view of the semi-permeable film 200 coupled tothe top surface of the mold compound 102 using the adhesive 300. Asshown, the semi-permeable film 200 covers the sensor cavities 104 thesensors 106 within the sensor cavities 104, as well as portions of thetop surface of the mold compound 102. In this example, the orifices 402are aligned in a manner such that after singulation, each orifice 402 islocated in a corner of a top surface of a corresponding sensor package.The adhesive 300 is exposed through the orifices 402, as shown. FIG. 5Bis a top-down view of the structure of FIG. 5A.

The method 3300 includes singulating the semiconductor dies in the arrayof semiconductor dies from each other (e.g., singulating the moldcompound) to produce multiple sensor packages (3306). The sensor packageincludes a portion of the adhesive, a portion of the semi-permeablefilm, and an orifice of the array of orifices, with the orifice exposingthe portion of the adhesive to an exterior of the sensor package (3306).FIG. 6A is a perspective view of an example post-singulation sensorpackage 600 produced using the example method 3300. FIG. 6B is atop-down view the sensor package 600. As shown in both FIGS. 6A and 6B,a portion of the semi-permeable film 200 couples to a top surface of thesensor package 600 using a portion of the adhesive 300. Further, asshown, the adhesive 300 and the semi-permeable film 200 areapproximately flush (i.e., exactly flush or within 1 mm of being flush)with each edge of the top surface of the sensor package 600. In someexamples, the adhesive 300 and the semi-permeable film 200 areapproximately flush with at least four edges of the top surface of thesensor package 600 (e.g., the mold compound 102). In some examples, theadhesive 300 and the semi-permeable film 200 are approximately flushwith at least three, at least two, or at least one edge of the topsurface of the sensor package 600. The approximately flush alignment ofthe adhesive 300 and/or the semi-permeable film 200 with the edges ofthe top surface of the sensor package 600 (e.g., the mold compound 102)is evidence of use of the method 3300 to manufacture a sensor package.Manual or semi-manual techniques for applying films to individual sensorpackages post-singulation will not produce such flush alignments.Coupling of the semi-permeable film 200 to the mold compound 102 andsubsequent singulation, however, will produce such flush alignments, andfor this reason the presence of such alignments is evidence of the useof the method 3300 described herein. Stronger adhesives 300 having theminimum adhesive strength range mentioned above may facilitate suchalignments pre- and post-singulation by preventing or mitigatingslippage.

As explained above, various advantages are realized by application ofthe method 3300. These advantages may be most pronounced when relativelylarge numbers of sensor packages are manufactured in parallel, e.g.,when the mold compound 102 described above covers more rather than fewersemiconductor dies. In such cases where multiple or large scales ofsensor packages are simultaneously produced using the method 3300,precision coverage of the sensors 106 by the semi-permeable film 200 isachieved by the act of package singulation rather than manual orsemi-manual alignment of a film on an individual sensor package.Accordingly, although these advantages of the method 3300 may berealized with any number of semiconductor dies, the advantages may bemore pronounced when the semiconductor dies are arranged in such apattern and have such a number that there are more semiconductor diesbounded on all sides by other semiconductor dies than there aresemiconductor dies not bounded on all sides by other semiconductor dies.Stated another way, the advantages of the method 3300 may be morepronounced when the number of semiconductor dies along the perimeter ofthe group of dies is less than the number of semiconductor dies notalong the perimeter of the group of dies (e.g., a square composed of2500 dies, with 198 dies on the perimeter and 2,302 interior dies). Thisis because, when the semi-permeable film 200 is approximately the samesize as the group of dies to be processed, proper alignment of thesemi-permeable film 200 may be more difficult to achieve for the diesalong the perimeter of the group of dies than for the group of dies notalong the perimeter. Misalignments are more readily detectable for diesalong the perimeter of the group, whereas misalignment for dies in theinterior area of the group becomes irrelevant post-singulation. Forgroups of dies that have fewer interior dies and more dies along theperimeter of the group (e.g., a square of four dies with four perimeterdies and no interior dies), a larger semi-permeable film 200 may beused, so that precise alignment of the semi-permeable film 200 with theedges of the mold compound 102 covering the semiconductor dies isirrelevant post-singulation. FIG. 7A illustrates the case where improperalignment of the semi-permeable film 200 on a mold compound 102 coveringfour semiconductor dies produces poor results. In the example of FIG.7A, only one semiconductor die 702 (on the bottom right) is fullycovered by the semi-permeable film 200 and will result in apost-singulation sensor package with proper alignment of thesemi-permeable film 200 with the edges of the top surface of the sensorpackage. FIG. 7B illustrates the case where improper alignment of thesemi-permeable film 200 on a mold compound 102 covering a larger numberof semiconductor dies produces good results for the interior diespost-singulation. In the example of FIG. 7B, many semiconductor dies 702are fully covered by the semi-permeable film 200 and will result inpost-singulation sensor packages with proper alignment of thesemi-permeable film 200 with the edges of the top surface of the sensorpackages. FIG. 7C illustrates the case where a large semi-permeable film200 on a mold compound 102 covering a smaller number of semiconductordies 702 produces good results for all of the dies post-singulation. Inthe example of FIG. 7C, all four semiconductor dies 702 are fullycovered by the semi-permeable film 200 and will result inpost-singulation sensor packages with proper alignment of thesemi-permeable film 200 with the edges of the top surface of the sensorpackages. FIG. 7D is a perspective view of the sensor package 600coupled to a PCB 700. Conductive terminals and solder connections areomitted for clarity and ease of explanation.

FIGS. 8A-19B are perspective, profile, and top-down views of anotherprocess flow for manufacturing a sensor package in accordance withvarious examples. FIG. 34 is a flow diagram of a method 3400 formanufacturing the sensor packages of FIGS. 8A-19B in accordance withvarious examples. Accordingly, FIGS. 8A-19B and 34 are now described intandem.

The method 3400 includes providing a first film having a first surface,the first surface having multiple rows of a first adhesive (3402). Themethod 3400 also includes coupling a second film to the first surface ofthe first film using the multiple rows of the first adhesive (3404).FIG. 8A is a perspective view of a structure that may be identical tothe structure of FIG. 1A, with numerals 800, 802, and 804 correspondingto numerals 100, 102, and 104, respectively. FIG. 8B is a top-down viewof the structure of FIG. 8A, with the numeral 806 corresponding tonumeral 106 in FIG. 1B. Accordingly, the description provided above forFIGS. 1A and 1B also apply to FIGS. 8A and 8B.

FIG. 9 is a perspective view of a non-permeable film 900. In examples,the non-permeable film 900 comprises polyimide. In other examples, thenon-permeable film 900 comprises silver epoxy-based materials,anisotropic conductive films and pastes, etc. The dimensions of thenon-permeable film 900, including length, width, and thickness, may varyas may be suitable. FIG. 10A is a perspective view of a film 1000. Inexamples, the film 1000 comprises plastic (e.g., high-densitypolyethylene), although other materials, such as silicone-coated kraftpaper, also may be used. Adhesive 1002 is applied to the film 1000. Inexamples, the adhesive 1002 is applied in multiple rows along a lengthof the film 1000, as shown. Other arrangements are contemplated, forexample, the adhesive 1002 may be applied in multiple rows along a widthof the film 1000. In examples, the adhesive 1002 comprises acrylates andadhesion-modified polymers customized to the surface properties ofinterest. In examples, the adhesive 1002 has an adhesive strengthranging from 0.88 N/mm² to 1.81 N/mm², and in some examples, theadhesive 1002 has an adhesive strength of at least 1 N/mm². These rangesare significant for reasons described below, e.g., insufficient adhesivestrength may result in films such as films 900 and 1000 becomingseparated. FIG. 10B is a top-down view of the structure of FIG. 10A. Asshown in FIGS. 11 and 12, the films 900, 1000 are then coupled togetherusing the adhesive 1002. In examples, alternatives may be used in lieuof an adhesive, for example, a thermal, laser, or chemical bondingtechnique may be used to couple the films 900, 1000 together so that theareas of the films 900, 1000 are fused together in the same areas aswith the adhesive 1002 and so that the fused portions of the films 900,1000 have the same physical dimensions as the adhesive 1002.

The method 3400 includes applying a second adhesive to a top surface ofa mold compound (3406). The mold compound covers multiple semiconductordies and includes multiple sensor cavities in the top surface of themold compound, where each of the multiple sensor cavities is verticallyaligned with a sensor of a corresponding one of the multiplesemiconductor dies (3406). FIGS. 13A and 13B show perspective andtop-down views of a structure produced by step 3406. The structure ofFIGS. 13A and 13B are identical to the structure of FIGS. 8A and 8B,except with the addition of an adhesive 1300. In examples, the adhesive1300 is the same as the adhesive 300 described above, and thus is notdescribed again here.

The method 3400 comprises coupling the second film to the top surface ofthe mold compound using the second adhesive, with the second filmcovering the multiple sensor cavities (3408). FIG. 14A is a perspectiveview of the structure of FIG. 12 coupled to the top surface of the moldcompound 802 (FIG. 13A) using the adhesive 1300 (FIG. 13A). As shown,the non-permeable film 900 abuts the adhesive 1300, and the film 1000faces away from the adhesive 1300. FIGS. 14B and 14C provide profile andtop-down views of the structure of FIG. 14A.

The method 3400 includes singulating the mold compound to produce asensor package, where the sensor package is coupled to a portion of thesecond film and to a portion of the first film (3410). FIG. 15A is aperspective view of the structure of FIG. 14A, except that a singulationprocess has been performed to separate the semiconductor dies from eachother and to produce multiple sensor packages 1500. The singulation maybe performed using any suitable technique, including mechanical sawing,laser sawing, etc. FIG. 15B is a profile view of the structure of FIG.15A, and FIG. 15C is a top-down view of the structure of FIG. 15A. Inexamples, the films 900, 1000 are approximately flush with the one, two,three, four, or more edges of the top surface of the correspondingsensor package 1500. Considerations in achieving such flush alignmentsof films 900, 1000 and edges of the top surface of the correspondingsensor package 1500 are similar to those provided above with respect tothe method 3300 and thus are not repeated here.

The method 3400 includes coupling the sensor package to a PCB (3412).FIGS. 16A, 16B, and 16C show perspective, profile, and top-down views ofthe sensor package 1500 coupled to a PCB 1700. Although the conductiveterminals on the sensor package 1500, solder connections, etc. are notexpressly shown for convenience and clarity, as explained above, theprocess of coupling a sensor package to a PCB involves dust, debris,pollution, corrosive cleaning solvents, etc. The non-permeable film 900protects the sensor package 1500, and particularly the sensor 806 insidethe sensor cavity 804, from such deleterious substances during the PCBmounting process.

The method 3400 includes using the portion of the first film to removethe portion of the first film and the portion of the second film fromthe sensor package (3414). FIGS. 17A, 17B, and 17C depict perspective,profile, and top-down views of step 3414. Only some of the film 1000 iscoupled to the non-permeable film 900, due to the arrangement of theadhesive 1002 in rows, as described above. The remainder of the film1000 is not coupled to the non-permeable film 900. Accordingly, thenon-coupled area of the film 1000 may function as a tab that can belifted and grasped to peel both the film 1000 and the non-permeable film900 off of the top surface of the sensor package 1500 (e.g., by a humanor by a pick-and-place tool). Because part of the film 1000 is coupledto the non-permeable film 900 using a strong adhesive 1002 as describedabove, the connection between the films 900, 1000 is sufficiently strongto withstand the forces applied when the films 900, 1000 are pulled offof the sensor package 1500. In addition, the adhesive 1300 is weakerthan the adhesive 1002, and thus the non-permeable film 900 is weaklycoupled to the top surface of the sensor package 1500 relative to thestrength of the adhesive 1002 between the films 900, 1000. FIGS. 18A,18B, and 18C are perspective, profile, and top-down views of the films900, 1000 being lifted off of the sensor package 1500. FIGS. 19A, 19B,and 19C are perspective, top-down, and profile views of the sensorpackage 1500 without the films 900, 1000. Although not expressly shown,a portion of the adhesive 1300 may remain on the top surface of thesensor package 1500 as residue.

The adhesive 1002 may have certain qualities that facilitate theperformance of the method 3400, and in particular, the removal of thefilms 900, 1000 in step 3414. For example, if the area of couplingbetween the films 900, 1000 is not sufficiently large, then when thefilm 1000 is pulled to remove the films 900, 1000, the film 1000 mayseparate from the film 900, leaving the film 900 coupled to the sensorpackage 1500. To prevent this, in examples each row of adhesive 1002 issufficiently wide so as to form a large coupling area between the films900, 1000. In examples, the width of each row of adhesive 1002 may rangebetween 5 millimeters and 30 millimeters. A row wider than this rangemay inappropriately increase costs and reduce the portion of the film1000 available for gripping during removal of the films 900, 1000, and arow narrower than this range may provide inadequate adhesion betweenfilms 900, 1000.

In addition, the benefits of a sufficiently wide row of adhesive 1002may be negated if the row is not properly aligned with a row ofsemiconductor dies when the film 1000 is being coupled to the moldcompound 802. For example, the film 1000 or a row of adhesive 1002 onthe film 1000 may be so misaligned relative to a corresponding row ofsemiconductor dies that, after singulation, some sensor packages 1500will have films 900, 1000 with little or no adhesive in between them.Even slight angular misalignments may become pronounced if the film 1000and/or mold compound 802 is sufficiently long. To mitigate such risks,in some examples the lengths of the film 1000 and/or mold compound 802may be limited, or extra precautions may be taken to mitigatemisalignments of the rows of adhesives 1002.

FIGS. 20A-25C are perspective, profile, and top-down views of anotherprocess flow for manufacturing a sensor package in accordance withvarious examples. FIG. 35 is a flow diagram of a method 3500 formanufacturing the sensor packages of FIGS. 20A-25C in accordance withvarious examples. In FIGS. 20A-25C and 35, tabs similar to thosedescribed above with reference to FIGS. 8A-19B and 34 are produced, butin a different manner. Accordingly, FIGS. 20A-25C and 35 are nowdescribed in tandem.

The method 3500 includes coupling a lengthwise portion of a compliantmember to a first surface of a film using a first adhesive (3502). Themethod 3500 also includes applying a second adhesive to a top surface ofa mold compound (3504). The mold compound covers multiple semiconductordies and includes multiple sensor cavities in the top surface of themold compound, with each of the multiple sensor cavities verticallyaligned with a sensor of a corresponding one of the multiplesemiconductor dies (3504). FIG. 20A is a perspective view of thestructure of FIG. 1A, with numerals 2000, 2002, and 2004 correspondingto numerals 100, 102, and 104, respectively. FIG. 20B is a top-down viewof the structure of FIG. 20A, with sensors 2006 visible in the sensorcavities 2004. The sensors 2006 are similar to the sensors 106 of FIG.1B. FIG. 21 is a perspective view of a non-permeable film 2100, such asthe non-permeable film 900 of FIG. 9. FIG. 22A is a perspective view ofthe structure of FIG. 20A, but with the addition of an adhesive 2200.The adhesive 2200 is similar to the adhesive 300 shown in FIG. 3. FIG.22B is a top-down view of the structure of FIG. 22A. FIG. 23A is aperspective view of the non-permeable film 2100 having lengthwiseportions 2302 of multiple compliant members 2300 coupled to thenon-permeable film 2100 as shown. In examples, the lengthwise portions2302 couple to the non-permeable film 2100 using a high strengthadhesive, such as the adhesive 1002 described above. In examples, thedescription provided above for the adhesive 1002 also applies to theadhesive used to couple the lengthwise portions 2302 to thenon-permeable film 2100. Because the compliant members 2300 arecompliant, portions 2304 of the compliant members 2300 that are notdirectly coupled to the non-permeable film 2100 using adhesive may bebent or folded at an approximate right angle with reference to thelengthwise portions 2302, as shown. Such a bend or fold produces a tabthat may later be grasped (e.g., by a human hand or a pick-and-placetool) to remove the compliant member 2300 and the non-permeable film2100 from a sensor package. Alternatives to adhesives include thermal,laser, and chemical bonding techniques. FIGS. 23B and 23C are profileand top-down views, respectively, of the structure of FIG. 23A.

The method 3500 comprises coupling a second surface of the film to thetop surface of the mold compound using the second adhesive, the filmcovering the multiple sensor cavities (3506). FIG. 24 is a perspectiveview of the structure of FIG. 23A coupled to the structure of FIG. 22A.Specifically, a bottom surface of the non-permeable film 2100 is coupledto the top surface of the mold compound 2002 using the adhesive 2200.

The method 3500 includes singulating the mold compound to produce asensor package, the sensor package coupled to a portion of the film andto a portion of the compliant member (3508). FIG. 25A is a perspectiveview of a sensor package 2500 comprising the mold compound 2002 andhaving coupled thereto the non-permeable film 2100 and the compliantmember 2300. The non-permeable film 2100 covers at least the sensorcavity 2004 and sensor 2006 of the sensor package 2500. FIG. 25B is atop-down view of the sensor package 2500, and FIG. 25C is a profile viewof the sensor package 2500.

The method 3500 includes coupling the sensor package to a PCB (3510).The non-permeable film 2100 protects at least the sensor cavity 2004 andthe sensor 2006 from debris, dust, pollution, corrosive substances, etc.during the PCB mounting process. After the sensor package 2500 has beencoupled to a PCB, the method 3500 comprises using the portion of thecompliant member to remove the portion of the film and the portion ofthe compliant member from the sensor package (3512). Thus, the portion2304 may be grasped and pulled to remove both the compliant member 2300and the non-permeable film 2100 from the sensor package 2500. Becausethe compliant member 2300 couples to the non-permeable film 2100 using astronger adhesive than the adhesive used to couple the non-permeablefilm 2100 to the mold compound 2002, pulling on the compliant member2300 causes both the compliant member 2300 and the non-permeable film2100 to detach from the sensor package 2500. The considerationsdescribed above for the adhesive 1002 (e.g., width of adhesive,alignment of adhesive with reference to rows of semiconductor dies) withreference to FIGS. 8A-19B and 34 apply to the adhesive used to couplethe compliant member 2300 to the non-permeable film 2100, and thus arenot repeated here. In examples, the compliant member 2300 has astiffness ranging from 0.2 Gigapascals (GPa) to 3 GPa. A stiffercompliant member 2300 may fail to adequately mitigate mechanical stressand may increase the possibility of damage during the removal process,while a less stiff compliant member 2300 may provide inadequate gripduring the removal process.

FIGS. 26A-32 are perspective, profile, top-down, and bottom-up views ofanother process flow for manufacturing a sensor package in accordancewith various examples. FIG. 36 is a flow diagram of a method 3600 formanufacturing the sensor packages of FIGS. 26A-32 in accordance withvarious examples. Accordingly, FIGS. 26A-32 and 36 are now described intandem.

The method 3600 includes coupling multiple flags to a first surface of afilm (3602). The method 3600 also includes applying an adhesive to a topsurface of a mold compound (3604). The mold compound covers multiplesemiconductor dies and includes multiple sensor cavities in the topsurface of the mold compound, with each of the multiple sensor cavitiesvertically aligned with a sensor of a corresponding one of the multiplesemiconductor dies (3604). FIG. 26A is a perspective view of a structurethat is the same as the structures of FIG. 1A, with numerals 2600, 2602,and 2604 corresponding to numerals 100, 102, and 104, respectively. FIG.26B is a top-down view of the structure of FIG. 26A, with sensors 2606inside the sensor cavities 2604. The sensors 2606 are the same as thesensors 106 shown in FIG. 1B. FIG. 27 is a top-down view of a carrier2700 (e.g., a paper carrier) having positioned thereupon multiple flags2702 (composed of, e.g., wax paper or PTFE). In examples, the flags 2702have a triangular shape, for instance when the flags 2702 are intendedfor subsequent positioning in a corner of a top surface of a sensorpackage, as described below. However, other shapes are contemplated andincluded in the scope of this disclosure, such as rectangles,semi-rectangles, semi-circles, etc. Such shapes may be better suited toplacement in areas other than corners of the top surfaces of sensorpackages, and, consequently, flags 2702 with such shapes may bepositioned differently on the carrier 2700. The flags 2702 may be sticky(or have an adhesive applied) on one surface, for example, the surfacefacing away (not touching) the carrier 2700. In examples, an adhesivestrength of the flags 2702 may range from 0.88 N/mm² and 1.81 N/mm²,with some examples having a minimum adhesive strength of 1.2 N/mm2. Anadhesive strength below these ranges may produce insufficient adhesionto prevent detachment of the flags 2702, while an adhesive strengthabove these ranges may be unnecessarily expensive or cumbersome to useduring manufacture. FIG. 28A is a perspective view of the structure ofFIG. 26A, but with the addition of an adhesive 2800. In examples, theadhesive 2800 corresponds to the adhesive 300 described above. FIG. 28Bis a top-down view of the structure of FIG. 28A. FIG. 29A is aperspective, top-down view of a non-permeable film 2900, which is thesame as the non-permeable film 2100 described above, both without andwith the flags 2702 coupled thereto. In examples, the flags 2702 arecoupled to the non-permeable film 2900 by laying the non-permeable film2100 on top of the carrier 2700, thus causing the sticky flags 2702 tocouple to the non-permeable film 2900 as shown. FIG. 29B is aperspective, bottom-up view of the structures of FIG. 29A.

The method 3600 includes coupling the multiple flags and the firstsurface of the film to the top surface of the mold compound using theadhesive, where the film covers the multiple sensor cavities (3606).FIG. 30A is a perspective view of the structure of FIG. 29A (includingthe flags 2702) coupled to the structure of FIG. 28A. As shown, thenon-permeable film 2900 covers the sensor cavities 2604 and the sensors2606 inside the sensor cavities 2604. FIG. 30B is a top-down view of thestructure of FIG. 30A.

The method 3600 includes singulating the mold compound to produce asensor package, where the sensor package is coupled to one of themultiple flags and to a portion of the film (3608). FIG. 31A is aperspective view of a sensor package 3100 having the non-permeable film2900 coupled to a top surface of the sensor package 3100 using theadhesive 2800. A flag 2702 is positioned in a corner of the top surfaceof the sensor package 3100, as shown. FIG. 31B is a top-down view of thestructure of FIG. 31A.

The method 3600 includes coupling the sensor package to a PCB (3610) andusing the one of the multiple flags to remove the portion of the filmfrom the sensor package (3612). FIG. 32 is a perspective view of thesensor package 3100 coupled to a PCB 3200, with conductive terminals,solder connections, etc. omitted for clarity and ease of explanation.The mounting of the sensor package 3100 may expose the sensor 2606 todust, debris, pollution, corrosive substances, but the non-permeablefilm 2900 covers and thus protects the sensor 2606 and the sensor cavity2604 from such harmful exposures. After the sensor package 3100 iscoupled to the PCB 3200, however, the flag 2702 may be used to removeboth the flag 2702 and the non-permeable film 2900 from the sensorpackage 3100, as shown. Specifically, the flag 2702 may be used toremove the flag 2702 and the non-permeable film 2900 because it is lessfirmly coupled to the adhesive 2800 than the non-permeable film 2900. Asa result, the flag 2702 is lifted off of the adhesive 2800 with relativeease, and the flag 2702 may then be grasped and pulled (e.g., by hand ora pick-and-place tool) to remove both the flag 2702 and thenon-permeable film 2900 from the sensor package 3100.

In examples, the flag 2702 is sized to be large enough so that it can begrasped with relative ease. Conversely, the flag 2702 should not be solarge that an adhesive seal does not form between the flag 2702 and thesensor cavity 2604. On the contrary, a seal is desirable between theflag 2702 and the sensor cavity 2604 so that there are no vulnerableingress points for dust, debris, pollution, corrosive substances, etc.to enter the sensor cavity 2604 and damage the sensor 2606. Accordingly,in some examples, the flag 2702 has an area approximately equivalent tothe horizontal cross-sectional area of the sensor cavity 2604. In someexamples, an area of the flag 2702 ranges from 0.5 mm² to 1 mm². In someexamples, to ensure an adequate seal between the flag 2702 and thesensor cavity 2604, the shortest distance between the flag 2702 and thesensor cavity 2604 is at least 1 mm.

In addition, the flag 2702 should be aligned with an edge of a topsurface of the sensor package 3100. Otherwise, the flag 2702 will be ofdiminished use in lifting the non-permeable film 2900 off of the sensorpackage 3100, or in some cases, portions of non-permeable film 2900 maybecome attached to the sensor package 3100 without also being coupled tothe flag 2702, making such portions of non-permeable film 2900 difficultto remove from the sensor package 3100. Thus, care should be taken tofacilitate proper alignment of the flag 2702 with the edge of the topsurface of the sensor package 3100. In the event that a relatively smalldegree of misalignment is still present after the non-permeable film2900 has been coupled to the mold compound 2602, the singulation processmay be adjusted to ensure that the flags 2702, post-singulation, arepresent on the edges of the top surfaces of the sensor packages 3100.

In general, each of the example methods described above produces a filmthat covers at least a sensor cavity of a sensor package or, inexamples, an entire top surface of a sensor package. Because these filmsprotect from exposure to debris, dust, pollution, corrosive substances,etc., removal of the films after PCB mounting reveals areas of thesensor packages that are free of damage from such exposure. In examples,the areas of the sensor packages free of damage from such exposure arecommensurate with the coverage provided by the corresponding films.Thus, in examples where a film covers an entire top surface of a sensorpackage, the entire top surface of the sensor package may be free fromevidence of exposure to damaging substances. Such an area that is freefrom damage due to corrosive and other harmful substances may beapproximately flush with one, two, three, four, or more edges of the topsurface of the sensor package. Such flush alignment with the edges ofthe top surface of the sensor package are possible with the methodsdescribed herein because the bounds of film protection are determined bythe singulation process and not by the ability of a human to accuratelyand precisely position a protective film on a sensor package. Otherpatterns evidencing protection from damaging substances are possible andare included in the scope of this disclosure.

In the foregoing discussion and in the claims, the terms “including” and“comprising” are used in an open-ended fashion, and thus mean“including, but not limited to . . . .” Also, the term “couple” or“couples” means either an indirect or direct connection. Thus, if afirst device couples to a second device, that connection may be througha direct connection or through an indirect connection via other devicesand connections. Similarly, a device that is coupled between a firstcomponent or location and a second component or location may be througha direct connection or through an indirect connection via other devicesand connections. An element or feature that is “configured to” perform atask or function may be configured (e.g., programmed or structurallydesigned) at a time of manufacturing by a manufacturer to perform thefunction and/or may be configurable (or re-configurable) by a user aftermanufacturing to perform the function and/or other additional oralternative functions. The configuring may be through firmware and/orsoftware programming of the device, through a construction and/or layoutof hardware components and interconnections of the device, or acombination thereof. Unless otherwise stated, “about,” “approximately,”or “substantially” preceding a value means +/−10 percent of the statedvalue.

The above discussion is illustrative of the principles and variousexamples of the present disclosure. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. The following claims should beinterpreted to embrace all such variations and modifications.

What is claimed is:
 1. A sensor package, comprising: a semiconductor diehaving a sensor; a mold compound covering a portion of the semiconductordie; a cavity formed in a top surface of the mold compound, the sensorin the cavity; an adhesive abutting the top surface of the moldcompound; and a semi-permeable film abutting the adhesive and coveringthe cavity, the semi-permeable film approximately flush with at leastfour edges of the top surface of the mold compound.
 2. The sensorpackage of claim 1, wherein the adhesive is approximately flush with theat least four edges of the top surface of the mold compound.
 3. Thesensor package of claim 1, wherein the adhesive is exposed to anexterior of the sensor package at a corner of the top surface of themold compound.
 4. The sensor package of claim 3, wherein the corner isin closer proximity to pin one of the sensor package than to any otherpin of the sensor package.
 5. The sensor package of claim 1, wherein thesemi-permeable film is composed of polytetrafluoroethylene (PTFE).
 6. Amethod, comprising: covering an array of semiconductor dies with a moldcompound, the mold compound having an array of cavities in a top surfaceof the mold compound, each cavity in the array of cavities verticallyaligned with a sensor of a corresponding semiconductor die in the arrayof semiconductor dies; coupling a semi-permeable film to the top surfaceof the mold compound using an adhesive, the semi-permeable film coveringthe array of cavities, the semi-permeable film having an array oforifices; and singulating the semiconductor dies in the array ofsemiconductor dies from each other to produce a sensor package, thesensor package including a portion of the adhesive, a portion of thesemi-permeable film, and an orifice of the array of orifices, theorifice exposing the portion of the adhesive to an exterior of thesensor package.
 7. The method of claim 6, wherein the semi-permeablefilm is approximately flush with at least four edges of the top surfaceof the mold compound.
 8. The method of claim 6, wherein the adhesive isapproximately flush with at least four edges of the top surface of themold compound.
 9. The method of claim 6, wherein the orifice exposes theportion of the adhesive to the exterior of the sensor package at acorner of the top surface of the mold compound.
 10. The method of claim9, wherein the corner is in closer proximity to pin one of the sensorpackage than to any other pin of the sensor package.
 11. The method ofclaim 10, wherein the semi-permeable film is composed ofpolytetrafluoroethylene (PTFE).
 12. A sensor package, comprising: asemiconductor die having a sensor; a mold compound covering a portion ofthe semiconductor die, an area of the mold compound and the sensorunaffected by corrosive substances, the area having edges that are flushwith edges of a top surface of the mold compound; and a cavity formed inthe top surface of the mold compound, the sensor in the cavity.
 13. Thesensor package of claim 12, wherein the top surface of the mold compoundis covered with an adhesive.
 14. The sensor package of claim 13, whereinthe adhesive has an adhesive strength ranging from 0.88 N/mm² to 1.81N/mm².
 15. A method, comprising: providing a first film having a firstsurface, the first surface having multiple rows of a first adhesive;coupling a second film to the first surface of the first film using themultiple rows of the first adhesive; applying a second adhesive to a topsurface of a mold compound, the mold compound covering multiplesemiconductor dies and including multiple cavities in the top surface ofthe mold compound, each of the multiple cavities vertically aligned witha sensor of a corresponding one of the multiple semiconductor dies;coupling the second film to the top surface of the mold compound usingthe second adhesive, the second film covering the multiple cavities;singulating the mold compound to produce a sensor package, the sensorpackage coupled to a portion of the second film and to a portion of thefirst film; coupling the sensor package to a printed circuit board(PCB); and using the portion of the first film to remove the portion ofthe first film and the portion of the second film from the sensorpackage.
 16. The method of claim 15, wherein the first adhesive has anadhesive strength ranging from 0.88 N/mm² to 1.81 N/mm².
 17. The methodof claim 15, wherein the second adhesive has an adhesive strengthranging from 0.88 N/mm² to 1.81 N/mm².
 18. The method of claim 15,wherein part of the portion of the first film couples to the portion ofthe second film using a portion of one of the multiple rows of the firstadhesive.
 19. The method of claim 15, wherein the first film comprisesplastic and the second film comprises polyimide.
 20. A method,comprising: coupling a lengthwise portion of a compliant member to afirst surface of a film using a first adhesive; applying a secondadhesive to a top surface of a mold compound, the mold compound coveringmultiple semiconductor dies and including multiple cavities in the topsurface of the mold compound, each of the multiple cavities verticallyaligned with a sensor of a corresponding one of the multiplesemiconductor dies; coupling a second surface of the film to the topsurface of the mold compound using the second adhesive, the filmcovering the multiple cavities; singulating the mold compound to producea sensor package, the sensor package coupled to a portion of the filmand to a portion of the compliant member; coupling the sensor package toa printed circuit board (PCB); and using the portion of the compliantmember to remove the portion of the film and the portion of thecompliant member from the sensor package.
 21. The method of claim 20,wherein the compliant member has a stiffness ranging from 0.2 GPa to 3GPa.
 22. The method of claim 20, wherein the film comprises polyimide.23. The method of claim 20, wherein the film is non-permeable.
 24. Amethod, comprising: coupling multiple flags to a first surface of afilm; applying an adhesive to a top surface of a mold compound, the moldcompound covering multiple semiconductor dies and including multiplecavities in the top surface of the mold compound, each of the multiplecavities vertically aligned with a sensor of a corresponding one of themultiple semiconductor dies; coupling the multiple flags and the firstsurface of the film to the top surface of the mold compound using theadhesive, the film covering the multiple cavities; singulating the moldcompound to produce a sensor package, the sensor package coupled to oneof the multiple flags and to a portion of the film; coupling the sensorpackage to a printed circuit board (PCB); and using the one of themultiple flags to remove the portion of the film from the sensorpackage.
 25. The method of claim 24, wherein the multiple flags are on apaper carrier when coupled to the first surface of the film.
 26. Themethod of claim 24, wherein the multiple flags comprise wax orpolytetrafluoroethylene (PTFE).
 27. The method of claim 24, wherein thefilm comprises polyimide.